1. Field of the Invention
The present invention relates to modular ventilation fan assemblies for electronics enclosures.
2. Description of Related Art
Modular ventilation fan assemblies, sometimes called fan tray assemblies (or more briefly, xe2x80x9cfan traysxe2x80x9d) are used for mounting ventilation fans to electronics enclosures, such as computer enclosures. Conductive enclosures are used to contain electromagnetic interference (EMI) generated by electronic equipment, and ventilation fans are often used for thermal control of their enclosed interior spaces. The fan tray provides for convenient mounting of one or more ventilation fans to the electronics enclosure while maintaining the EMI-shielding integrity of the enclosure. The fan tray may also provide a convenient location for mounting a control circuit for the ventilation fan or fans in the fan tray.
The ventilation fan itself is usually a modular unit that includes a rotor and a motor encased in a plastic housing. As such, it does not provide EMI shielding and may itself be a source of EMI. Fan trays therefore typically provide metal grills on opposite sides of the fan to electromagnetically isolate the ventilation fan from the environment outside of the fan tray, while allowing for the passage of air through the fan tray. At the same time, the metal grills and sheet metal walls of the fan tray maintain electromagnetic isolation for the interior of the electronics enclosure and serve as part of the wall thereof.
Fan trays are often mounted to the electronics enclosures using a pair of opposing side rails that engage corresponding rails in the electronics enclosure. The fan tray may be mounted to, and removed from, the enclosure by sliding the tray along these rails. The fan tray may be secured to the enclosure using a screw or like fastener after being slid into place along the rails. As modular assemblies, prior art fan trays facilitate assembly and repair of electronics enclosures, particularly when a fan control circuit is included in the fan tray.
However, prior art fan trays are subject to various shortcomings. They are typically assembled from sheet metal components and fastened together using screws or like fasteners. Screws are also used to fasten assembled fan trays to electronics enclosures. The use of screws or like fasteners increases assembly and removal time, and increases the number of tray components. Both of these factors can add substantially to the cost of fan trays, as well as create inconveniences for users.
A further disadvantage of prior art fan trays is that the fan control circuit on a printed circuit board (PCB) is fixed to the sheet metal components of the tray. Attachment of the PCB to the tray may require the use of separate fasteners, which are undesirable for reasons noted above. In addition, in whatever manner the PCB is attached, fixing the controller PCB to the fan tray housing may limit the ease with which it may be electrically connected to the electronics in the enclosure. The controller PCB has an outwardly-facing electrical connector socket for mating with a matching plug connected to wiring in the electronics enclosure. Fixing the PCB (and hence, the connector socket) to the fan tray may encumber engagement of the connector plug, necessitating additional manipulation during assembly. Other shortcomings of prior art fan trays include air grills that are too restrictive of air flow.
It is therefore desirable to provide a fan tray that overcomes these and other shortcomings of prior art fan trays, while retaining their advantages.
The present invention provides a fan tray assembly that requires no removable fasteners or other loose hardware in its assembly. The fan tray may be used with prior art electronics enclosures while requiring minimal or no modifications to the enclosure. Like prior art trays, it may be installed and removed from an enclosure by sliding along an engaging pair of rails. It may be assembled from inexpensive sheet metal pieces (shells) that are self-aligning and self-fastening, for decreased assembly cost. For this purpose, the shells may include attachment features for attaching the shells to one another, and retention features for retaining a ventilation fan between the shells. the attachment and retention features may be formed integrally with the shells from the same sheet of material. Taken together, the attachment and retention features may reduce or eliminate the need to use loose hardware or adhesive for fastening during assembly.
Advantageously, the fan tray also does not require use of a separate fastener to secure it to an enclosure. Instead, it may be secured to an enclosure using a spring loaded latch that is integrated into the fan tray. The latch automatically engages when the fan tray is fully inserted into the engaging rails of an enclosure. It may be configured to be disengaged for removal of the fan tray by a one-handed, squeeze and pull operation, greatly increasing the convenience of assembly and repair.
The fan tray also provides for attachment of a controller PCB without the use of any fasteners. The PCB, defining an x-y plane, is oriented with an electrical connector extending from the fan tray along a z-axis perpendicular to the x-y plane of the PCB. The PCB is substantially fixed with respect to its z-axis but is permitted to float with respect to the x-y plane. Misalignment between the connector and a mating connector fixed to the electronics enclosure may readily be corrected for within the limits of the float. Accordingly, the connector may be readily engaged by merely applying pressure along the z-axis, which is parallel to the side rails. An electrical connection to the fan tray assembly may thus be established by inserting the fan tray into the enclosure, without any need for a separate operation to mate the electrical connectors. Likewise, the electrical connectors preferably can be disengaged merely by withdrawing the fan tray. In addition, the fan tray is preferably configured so that proper orientation of the PCB is ensured during assembly.
Other beneficial features of the fan tray assembly include improved air grills that substantially improve air flow through the fan tray. A more complete understanding of the fan tray assembly will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the preferred embodiment. Reference will be made to the appended sheets of drawings which will first be described briefly.